This invention relates to a liquid pressure transfer method, and more particularly to a liquid pressure transfer printing method for applying a pattern for decoration specifically intended for a workpiece such as a steering wheel for an automobile or the like which includes a rod-like element curved to form a predetermined apparent plane to the workpiece.
For example, a steering wheel for an automobile has a core made of a metal material so as to exhibit strength of at least a predetermined level. The core is provided therearound with a grip surface, which is formed of a material such as a plastic material, a wooden material, a leather material or the like, which is selected depending on requirements such as operability of the steering wheel, decorative characteristics thereof and the like. For example, a steering wheel provided thereon with a wooden surface is evaluated to be a high-quality article, because it exhibits both satisfactory operability and decorative characteristics and requires considerable labor and time for manufacturing. However, a recent tendency to reconsider the easygoing use of a natural material in view of protecting the natural environment, and a demand for reduction of a manufacturing cost had led to development of liquid pressure transfer printing techniques. These techniques involve transfer printing on a plastic steering wheel material in place of a wooden steering wheel material to apply a woodgrain pattern for decoration thereto.
Application of a decorative pattern to a workpiece by liquid pressure transfer permits formation of a natural pattern which exhibits satisfactory conformability to a configuration of the workpiece, resulting in the technique being extensively practiced on a variety of workpieces. However, application of such liquid pressure transfer to, for example, a steering wheel encounters some important problems. A conventional steering wheel made of a wooden material is manufactured by subjecting two wooden rod-like materials which are semicircular in section to a treatment by moistening and heating to bend them into an annular shape, and then bonding them to each other while interposing a core therebetween. Thus, of course the wooden materials are each so arranged that a straight grain extends in a circumferential direction of the steering wheel. Such arrangement of the straight grain permits a user to have a sense of security or a sense of reliability.
Unfortunately, in application of a decorative pattern to a workpiece by liquid pressure transfer, a transfer film having a transfer pattern formed thereon is supported on a surface of a transfer liquid while being floated thereon, so that exact positioning or registration between the transfer film and the workpiece is relatively difficult. Thus, in the prior art, a continuously-formed decorative pattern such as a woodgrain pattern, a natural stone pattern, or a carbon fiber pattern is arranged all over the transfer film so as to allow misregistration which occurs between the transfer film and the workpiece. Consequently, a decorative pattern similar to a natural material is provided irrespective of a portion of the pattern transferred to the workpiece. Nevertheless, development of techniques of reproducing a transfer pattern specifically intended for a desired product such as, for example, techniques of arranging a straight grain pattern in a circumferential direction of a steering wheel, are still demanded.
The present invention has been made in view of the foregoing disadvantage of the prior art.
Accordingly, it is an object of the present invention to provide a liquid pressure transfer method which is capable of applying a decorative pattern specifically intended for a specific or desired workpiece such as a steering wheel or the like to the workpiece.
It is another object of the present invention to provide a transfer film which is capable of facilitating application of a decorative pattern specifically intended for a workpiece such as a steering wheel or the like to the workpiece.
It is a further object of the present invention to provide a product decorated according to the liquid pressure transfer method described above.
In accordance with one aspect of the present a liquid pressure transfer method for carrying out liquid pressure transfer printing on a workpiece such as a steering wheel is provided. The liquid pressure transfer method includes the step of supporting a transfer film on a surface of a transfer liquid while floating it thereon. The transfer film has a transfer pattern for decoration printed thereon. The liquid pressure transfer method also includes the step of downwardly immersing a workpiece in the transfer liquid to transfer the transfer pattern to a surface of the workpiece, to thereby decorate the workpiece. The workpiece includes a rod-like element curved into a loop-like shape, resulting in it being formed in an apparent geometric plane which permits the workpiece to be recognized as a whole. The transfer pattern is formed to have a configuration corresponding to a configuration of the apparent plane of the workpiece, and is arranged on a required position of the transfer film. The workpiece is handled so as to approach the transfer film from a position above the transfer pattern corresponding to the transfer pattern and is then immersed in the transfer liquid. Therefore, the transfer film bonds to the rod-like element of the workpiece in a manner to circumferentially surround the rod-like element continuously from a bottom of the rod-like element to a top thereof on the basis of a diametric section of the rod-like element, resulting in the transfer pattern being transferred to at least the rod-like element of the workpiece.
The liquid pressure transfer method thus constructed permits the workpiece, such as a steering wheel or the like which includes the rod-like element curved to form a predetermined apparent plane, to be readily and positively decorated with a transfer pattern specifically intended for the workpiece.
In a preferred embodiment of the present invention, an approach attitude angle defined between the apparent plane of the workpiece and the surface of the transfer liquid is set to be within a range of xc2x115xc2x0. This permits the optimum approach attitude angle to be set depending on a type of the transfer pattern, as well as a size of the workpiece, a configuration thereof and the like.
In a preferred embodiment of the present invention, the workpiece is immersed in the transfer liquid in a substantially vertical direction. Such vertical lowering of the workpiece to the surface of the transfer liquid facilitates transfer of the transfer pattern to the workpiece.
In a preferred embodiment of the present invention, the transfer film is provided thereon with reference position marks for enabling relative registration between the transfer pattern and the workpiece. This permits positioning or registration between the transfer pattern and the workpiece to be readily attained while preventing misregistration of the transfer film.
In accordance with another aspect of the present invention, a transfer film is provided. The transfer film includes a film body which has a transfer operation surface defined thereon. The transfer operation surface has a predetermined transfer pattern previously printed thereon in transfer ink. When transfer is to be carried out, the transfer operation surface is coated thereon with an activator to permit a portion of the transfer operation surface to which the transfer ink is applied to exhibit stickiness. The transfer film is supported on a surface of a transfer liquid while being floated thereon. The transfer pattern is transferred to a surface of a workpiece by a liquid pressure produced when the workpiece is downwardly immersed in the transfer liquid. The transfer film is applied to the workpiece including a rod-like element curved into a loop-like shape, resulting in the workpiece being formed with an apparent plane which permits the workpiece to be recognized as a whole. The transfer pattern is formed to have a configuration corresponding to a configuration of the apparent plane of the workpiece and arranged on a required position of the transfer film. The transfer film thus constructed permits the transfer pattern specifically intended for the workpiece to be readily applied to the workpiece, to thereby facilitate decoration of the workpiece.
In a preferred embodiment of the present invention, the workpiece is a steering wheel. The transfer pattern is formed to have a substantially annular shape in correspondence to the apparent plane of the steering wheel. Thus, in the present invention, although distortion of the pattern is varied depending on a position on a circumference of a diametric section of the rod-like element of the workpiece, the pattern distortion in a circumferential direction of the whole steering wheel is substantially the same irrespective of a position on the rod-like element in the circumferential direction thereof. Thus, the transfer printing may be carried out while rendering the pattern distortion inconspicuous.
In a preferred embodiment of the present invention, the transfer pattern is formed to have a substantially annular shape by taking in pattern data having a plane rectangular shape and then converting the pattern data into pattern data having a round shape. This permits the transfer pattern specifically intended for the workpiece to be more exactly reproduced on the workpiece.
In accordance with a further aspect of the present invention, there is provided a decorated product to which a predetermined decorative pattern is applied by subjecting a workpiece such as a steering wheel or the like including a rod-like element to liquid pressure transfer printing in which the workpiece is downwardly immersed in a transfer liquid which supports a transfer film having a transfer pattern for decoration printed on a surface thereof while floating it on the transfer liquid. Therefore, the transfer pattern is applied to at least the rod-like element of the workpiece. The workpiece is operated so as to permit the transfer pattern to be printed on the rod-like element of the workpiece in a manner to circumferentially surround the rod-like element continuously from a bottom of the rod-like element to a top thereof on the basis of a diametric section of the rod-like element. Consequently, transfer of the transfer pattern to the workpiece is carried out according to the above-described liquid pressure transfer method while ensuring exact reproducibility of the transfer pattern.
Such construction permits the transfer pattern to be more exactly reproduced on a variety of workpieces of a closed loop shape or an open loop shape including, for example, a hula hoop, rings in gymnastic, a towel ring, a chair back, a handrail and the like in addition to the steering wheel while minimizing distortion of the transfer pattern.